Zapmail MCP Server

Does the description disclose side effects, auth requirements, rate limits, or destructive behavior?

With no annotations provided, the description carries full burden. It discloses that this is a read operation ('Retrieve') and mentions authentication requirements ('for the authenticated user'), but lacks details about rate limits, pagination, error conditions, or response format. The statement 'This endpoint returns comprehensive details' is somewhat helpful but vague about what 'comprehensive' entails.

Agents need to know what a tool does to the world before calling it. Descriptions should go beyond structured annotations to explain consequences.

Is the description appropriately sized, front-loaded, and free of redundancy?

The description is efficiently structured in three sentences that progressively add information: purpose, details returned, and invocation instruction. The final sentence 'Invoke this endpoint' is somewhat redundant but doesn't significantly detract from overall conciseness. Most sentences earn their place by adding value.

Shorter descriptions cost fewer tokens and are easier for agents to parse. Every sentence should earn its place.

Given the tool's complexity, does the description cover enough for an agent to succeed on first attempt?

For a read operation with 7 parameters and no output schema, the description provides adequate but minimal context. It covers the purpose and scope but lacks details about response format, error handling, or practical usage examples. With no annotations and no output schema, the description should ideally provide more behavioral guidance to compensate for these gaps.

Complex tools with many parameters or behaviors need more documentation. Simple tools need less. This dimension scales expectations accordingly.

Does the description clarify parameter syntax, constraints, interactions, or defaults beyond what the schema provides?

Schema description coverage is 100%, so the schema already documents all 7 parameters thoroughly. The description doesn't add any parameter-specific information beyond what's in the schema. The baseline score of 3 is appropriate since the schema does the heavy lifting, though the description could have explained which parameters are relevant for this specific endpoint.

Input schemas describe structure but not intent. Descriptions should explain non-obvious parameter relationships and valid value ranges.

Does the description clearly state what the tool does and how it differs from similar tools?

The description clearly states the action ('Retrieve all DNS Shield subscriptions') and specifies the resource scope ('for the authenticated user', 'both Monthly and LTD'). It distinguishes from sibling tools like 'get_all_subscriptions_13489431e0' by focusing specifically on DNS Shield subscriptions rather than all subscription types.

Agents choose between tools based on descriptions. A clear purpose with a specific verb and resource helps agents select the right tool.

Does the description explain when to use this tool, when not to, or what alternatives exist?

The description implies usage context by specifying 'for the authenticated user' and mentioning DNS Shield subscriptions, but doesn't explicitly state when to use this tool versus alternatives like 'get_all_subscriptions_13489431e0' or 'get_subscriptions_25778521e0'. No explicit when-not-to-use guidance or prerequisite information is provided.

Agents often have multiple tools that could apply. Explicit usage guidance like "use X instead of Y when Z" prevents misuse.